title: Catheter-tissue contact force determines atrial electrogram characteristics before and lesion efficacy after antral pulmonary vein isolation in humans.
abstract: BACKGROUND
  Electrogram (EGM) characteristics are used to infer catheter-tissue contact. We examined if (a) atrial EGM characteristics predicted CF and (b) compared the value of CF versus other surrogates for predicting lesion efficacy.
  
  
  RESULTS
  Twelve paroxysmal AF patients underwent pulmonary vein isolation using radiofrequency (RF) ablation facilitated by a novel CF-sensing catheter. Operators were blinded to CF. EGM amplitude, width, and morphology were measured pre- and post-RF. At each RF site, average CF, force-time integral (FTI), impedance fall, time to impedance plateau, maximum power, catheter tip temperature, and total energy delivered were recorded. An effective lesion was defined based on previously validated EGM criteria for transmural lesions. There was a moderate correlation between CF and EGM amplitude (r = 0.19) and EGM width (r = -0.22). Pre-RF, EGM amplitude, and width had modest to poor discriminative capacity for identifying preablation CF (e.g., EGM amplitude identified CF>20 g with sensitivity and specificity of 67% and 60%, respectively). Preablation CF, FTI, and total energy delivered during RF were the only independent predictors of effective lesion formation. Neither pre-RF EGM amplitude/width nor power, temperature, and impedance changes during RF predicted effective lesion formation. An average CF >16 g or FTI >404 g*s had excellent sensitivity and specificity (>80%) for identifying an effective lesion.
  
  
  CONCLUSIONS
  EGM characteristics do not reliably predict either CF before the onset of RF, nor do they predict the likelihood of an effective lesion. CF parameters were superior to power, temperature, and impedance changes during RF in predicting lesion efficacy.
authors.affiliation: Department of Cardiology, Parkville, Victoria, Australia; Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kumar
authors.forename: Martin
authors.initials: M
authors.lastname: Chan
authors.forename: Justin
authors.initials: J
authors.lastname: Lee
authors.forename: Michael C G
authors.initials: MC
authors.lastname: Wong
authors.forename: Matias
authors.initials: M
authors.lastname: Yudi
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Morton
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Spence
authors.forename: Karen
authors.initials: K
authors.lastname: Halloran
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kistler
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kalman
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation / Q000295:instrumentation / Q000379:methods; D011667:Pulmonary Veins / Q000503:physiopathology / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D016896:Treatment Outcome
keywords: atrial electrogram; atrial fibrillation; average contact force; catheter ablation; catheter-tissue contact force; energy; force-time integral; impedance; lesion efficacy; maximum power; radiofrequency; tip temperature